The present invention pertains to the art of liquid dispensers, and, more particularly, to a dispensing device for accurately dispensing small droplets of liquid. The invention is particularly applicable for use as an eyedropper and will be described with particular reference thereto although it will be appreciated that the invention has other and broader applications.
Medicant drop dispensers of the type to which the present invention pertains are available in various sizes and shapes for the numerous medicines and solutions which are available for the care and comfort of the human eye. Heretofore, such dispensers have basically comprised a relatively small compressible plastic container or vial provided with a dispensing cap. The cap is generally provided with a dispensing member or nozzle having a small orifice or opening therethrough.
One problem associated with conventional eyedroppers is the difficulty of accurately controlling the amount of medicine dispensed, i.e., the number and size of drops dispensed. Most conventional eyedrop dispensers heretofore provided a minute orifice or opening in the nozzle or dispenser portion of the cap. The larger the opening, the less pressure required to be exerted on the container and the more freely the medicant is dispensed. To provide a slower dispensing rate, the orifice in the nozzle or dispenser member is usually restricted in size, which then requires more pressure to be exerted on the container to force the medicant through the smaller opening. This type of dispenser does not provide the accuracy and control necessary for today's medicants. Accurately controlling the rate and placement of the drops are especially important, since most medicants for the human eye are extremely expensive and a single drop can cost upwards of several dollars. Thus, the loss or waste of even a few drops can present a substantial expense.
An additional problem associated with most drop dispensers known heretofore is the transfer of bacteria from the eye or an external source to the sterile medicant within the container. As mentioned above, drop dispensers generally provide a minute orifice or opening in the nozzle portion of the cap, and have a continuous passageway communicating such orifice with the interior of the container and the medicant therein. Contact between the surface of the orifice or nozzle and the eye surface or another external surface can contaminate the nozzle with bacteria. Sterile medicant from the container can then come in contact with the bacteria on the nozzle when drops are being dispensed. The medicant at the orifice or tip area of the nozzle which is not dispensed is drawn back or can seep back into the sterile medicant and thereby contaminate it.